Merge remote-tracking branch 'remotes/gkurz/tags/9p-next-2020-02-08' into staging

9p patches:
- some more protocol sanity checks
- qtest for readdir
- Christian Schoenebeck now official reviewer

# gpg: Signature made Sat 08 Feb 2020 08:38:10 GMT
# gpg:                using RSA key B4828BAF943140CEF2A3491071D4D5E5822F73D6
# gpg: Good signature from "Greg Kurz <groug@kaod.org>" [full]
# gpg:                 aka "Gregory Kurz <gregory.kurz@free.fr>" [full]
# gpg:                 aka "[jpeg image of size 3330]" [full]
# Primary key fingerprint: B482 8BAF 9431 40CE F2A3  4910 71D4 D5E5 822F 73D6

* remotes/gkurz/tags/9p-next-2020-02-08:
  MAINTAINERS: 9pfs: Add myself as reviewer
  tests/virtio-9p: added readdir test
  hw/9pfs/9p-synth: added directory for readdir test
  9pfs: validate count sent by client with T_readdir
  9pfs: require msize >= 4096
  tests/virtio-9p: add terminating null in v9fs_string_read()

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>

4 files changed, 56 insertions, 0 deletions

diff --git a/hw/9pfs/9p-synth.c b/hw/9pfs/9p-synth.c
index 54239c9bbf..7eb210ffa8 100644
--- a/hw/9pfs/9p-synth.c
+++ b/hw/9pfs/9p-synth.c
@@ -578,6 +578,25 @@ static int synth_init(FsContext *ctx, Error **errp)
                                        NULL, v9fs_synth_qtest_flush_write,
                                        ctx);
         assert(!ret);
+
+        /* Directory for READDIR test */
+        {
+            V9fsSynthNode *dir = NULL;
+            ret = qemu_v9fs_synth_mkdir(
+                NULL, 0700, QTEST_V9FS_SYNTH_READDIR_DIR, &dir
+            );
+            assert(!ret);
+            for (i = 0; i < QTEST_V9FS_SYNTH_READDIR_NFILES; ++i) {
+                char *name = g_strdup_printf(
+                    QTEST_V9FS_SYNTH_READDIR_FILE, i
+                );
+                ret = qemu_v9fs_synth_add_file(
+                    dir, 0, name, NULL, NULL, ctx
+                );
+                assert(!ret);
+                g_free(name);
+            }
+        }
     }
 
     return 0;
diff --git a/hw/9pfs/9p-synth.h b/hw/9pfs/9p-synth.h
index af7a993a1e..036d7e4a5b 100644
--- a/hw/9pfs/9p-synth.h
+++ b/hw/9pfs/9p-synth.h
@@ -55,6 +55,11 @@ int qemu_v9fs_synth_add_file(V9fsSynthNode *parent, int mode,
 #define QTEST_V9FS_SYNTH_LOPEN_FILE "LOPEN"
 #define QTEST_V9FS_SYNTH_WRITE_FILE "WRITE"
 
+/* for READDIR test */
+#define QTEST_V9FS_SYNTH_READDIR_DIR "ReadDirDir"
+#define QTEST_V9FS_SYNTH_READDIR_FILE "ReadDirFile%d"
+#define QTEST_V9FS_SYNTH_READDIR_NFILES 100
+
 /* Any write to the "FLUSH" file is handled one byte at a time by the
  * backend. If the byte is zero, the backend returns success (ie, 1),
  * otherwise it forces the server to try again forever. Thus allowing
diff --git a/hw/9pfs/9p.c b/hw/9pfs/9p.c
index b0e445d6bd..9e046f7acb 100644
--- a/hw/9pfs/9p.c
+++ b/hw/9pfs/9p.c
@@ -1363,8 +1363,20 @@ static void coroutine_fn v9fs_version(void *opaque)
         s->proto_version = V9FS_PROTO_2000L;
     } else {
         v9fs_string_sprintf(&version, "unknown");
+        /* skip min. msize check, reporting invalid version has priority */
+        goto marshal;
     }
 
+    if (s->msize < P9_MIN_MSIZE) {
+        err = -EMSGSIZE;
+        error_report(
+            "9pfs: Client requested msize < minimum msize ("
+            stringify(P9_MIN_MSIZE) ") supported by this server."
+        );
+        goto out;
+    }
+
+marshal:
     err = pdu_marshal(pdu, offset, "ds", s->msize, &version);
     if (err < 0) {
         goto out;
@@ -2422,6 +2434,7 @@ static void coroutine_fn v9fs_readdir(void *opaque)
     int32_t count;
     uint32_t max_count;
     V9fsPDU *pdu = opaque;
+    V9fsState *s = pdu->s;
 
     retval = pdu_unmarshal(pdu, offset, "dqd", &fid,
                            &initial_offset, &max_count);
@@ -2430,6 +2443,14 @@ static void coroutine_fn v9fs_readdir(void *opaque)
     }
     trace_v9fs_readdir(pdu->tag, pdu->id, fid, initial_offset, max_count);
 
+    /* Enough space for a R_readdir header: size[4] Rreaddir tag[2] count[4] */
+    if (max_count > s->msize - 11) {
+        max_count = s->msize - 11;
+        warn_report_once(
+            "9p: bad client: T_readdir with count > msize - 11"
+        );
+    }
+
     fidp = get_fid(pdu, fid);
     if (fidp == NULL) {
         retval = -EINVAL;
diff --git a/hw/9pfs/9p.h b/hw/9pfs/9p.h
index 8d07a0b301..b8f72a3bd9 100644
--- a/hw/9pfs/9p.h
+++ b/hw/9pfs/9p.h
@@ -100,6 +100,17 @@ typedef enum P9ProtoVersion {
     V9FS_PROTO_2000L = 0x02,
 } P9ProtoVersion;
 
+/**
+ * @brief Minimum message size supported by this 9pfs server.
+ *
+ * A client establishes a session by sending a Tversion request along with a
+ * 'msize' parameter which suggests the server a maximum message size ever to be
+ * used for communication (for both requests and replies) between client and
+ * server during that session. If client suggests a 'msize' smaller than this
+ * value then session is denied by server with an error response.
+ */
+#define P9_MIN_MSIZE    4096
+
 #define P9_NOTAG    UINT16_MAX
 #define P9_NOFID    UINT32_MAX
 #define P9_MAXWELEM 16